Due to their open structure and large surface area, molecular sieves have been widely used in catalysis, ion exchange, adsorption, separation and so on. Therefore, the research on molecular sieves is of high importance for the chemical industry, and there is a strong need to develop new synthetic routes for molecular sieves. In the early stage of the molecular sieve research, molecular sieves were synthesized under hydrothermal conditions, and only limited types of molecular sieves were synthesized including zeolites A, X, Y, L, and so on. In the late 1960s, the introduction of organic template agents led to the synthesis of various novel molecular sieves, such as ZSM-5, Beta, which are of high importance in the chemical industry.
In recent years, researchers started to use organotemplate-free methods for the synthesis of zeolite molecular sieves, such as ECR-1, ZSM-34, Beta, ZSM-12, RuB-13 and so on. The organotemplate-free method avoids several issues related to the use of organic templates in the zeolite synthesis, for example, unfavorable costs, waste of energy and release of hazardous gases from the template calcination process as well as the inherent toxicity of many organic template agents. More recently, the group of Xiao has successfully synthesized Silicate-1, ZSM-5, ZSM-39 and other zeolites by using a novel synthetic method which includes grinding the raw materials in a solid-state under solvent-free conditions and subsequent crystallization (called solid-state method for short). This solid-state method minimizes the consumption of aqueous solvents, and simplifies the molecular sieve synthesis, which has the potential to reduce the overall production cost as well as the waste that has to be discharged.
However, the above two synthetic methods both have their own disadvantages. The organotemplate-free synthetic method containing a hydrothermal process requires the consumption of a large amount of aqueous solvent; whereas for the solid-state method, organic template with all inherent issues has to be employed. The present invention provides a novel organotemplate-free and solid-state synthetic method which enables a “green” synthetic route for molecular sieves, leading to a low cost production, low energy consumption and almost zero pollution.